Apparatus for treatment of sheet structures

ABSTRACT

Apparatus for the continuous treatment of sheet structures with a gaseous fluid under low controlled mechanical pressures, in which the sheet structure is supported between a nondeformable, impervious movable member and a porous, conformable, movable member, the porous member forming for at least part of the distance over which it and the rigid member are in contact with the sheet structure a wall of a chamber within which the treatment fluid is maintained.

United States Patent Parr [ 1 Feb. 1,1972

[54] APPARATUS FOR TREATMENT OF SHEET STRUCTURES [72] Inventor: William Geoffrey Parr, Pontypool, En-

gland [73] Assignee: Imperial Chemical Industries Limited,

London, England [22] Filed: May 7,1970

211 App]. No.: 35,521

[30] Foreign Application Priority Data May 19, 1969 Great Britain ..25,492/69 US. Cl ..34/l22, 34/118, 34/123 ..F26b 11/02 Field ofSearch ..34/114,116,118,122,123,

[56] References Cited UNITED STATES PATENTS 2,197,463 4/1940 Bradner ..34/ l 22 3,320,675 5/1967 Chaikin et al ..34/1 18 X Primary Examiner-Carroll B. Dority, Jr. Attorney-Cushman, Darby & Cushman [5 7] ABSTRACT Apparatus for the continuous treatment of sheet structures with a gaseous fluid under low controlled mechanical pressures, in which the sheet structure is supported between a nondeformable, impervious movable member and a porous, conformable, movable member, the porous member forming for at least part of the distance over which it and the rigid member are in contact with the sheet structure a wall of a chamber within which the treatment fluid is maintained.

10 Claims, 2 Drawing Figures PATENTEU F581 1812, 3.638329 Inventor Z i y Nor/$33:

APPARATUS FOR TREATMENT OF SHEET STRUCTURES the fluid is contained. Much effort has been apparent from numerous patent specifications and publications to provide apparatus which is capable of achieving such exposure without, on the one hand, exerting undue pressure on the structure, and without, on the other hand, diluting the fluid with air and losing the fluid to the atmosphere in uneconomic quantities. Some publications have proposed minimizing fluid losses to the atmosphere by providing the treatment chamber with inlet and/or outlet seals through which the structure may be passed but which serve to reduce fluid losses to acceptable amounts. Those devices, however, are often unacceptable when delicate sheet structures are required to be treated since the pressure exerted by the seals may damage the structure. The passage of sheet structures through unsealed chambers has also been proposed but we have found that the properties of structures so treated are nonuniform presumably because of uneven exposure to the treatment fluid, quite apart from the uneconomical loss of the fluid to'the atmosphere. In another type of apparatus of the kind specified the sheet structure is supported on a rigid perforated sheet which forms one wall of the fluid containing chamber. In order to reduce fluid losses the sheet structure may be sandwiched between the perforated plate and a second, imperforate sheet. In continuous processes the perforated sheet may be in the form of a rotating cylinder over which the sheet structure passes. However, no imperforate sheet can then be used to minimize fluid losses and the structure is treated only at points immediately adjacent to the perforations in the support surface. The latter objects can be minimized by providing a very large number of fine perforations but the strength of the support material is correspondingly reduced and complicated internal reinforcement may have to be provided.

We have now invented a simple, cheap apparatus for the continuous treatment of sheet structures with a gaseous fluid under low, controlled mechanical pressures and accordingly the invention comprises apparatus of the kind specified in which the sheet structure is supported between a rigid, impervious movable member and a porous, conformable, movable member, both members being arranged to move at the same surface speed as the sheet structure and to exert thereupon a controlled pressure, the porous member being arranged to form for at least part of the distance over which it and the rigid member are in contact with the sheet structure, a wall of a chamber within which the treatment fluid is maintained, thereby permitting the fluid to percolate through the porous member and expose continuously the sheet structure to the said treatment fluid.

By low mechanical pressure we mean pressures in the range 35-140 g. cm. preferably in the range 4-10 g. emf.

The rigid movable member and the porous movable member should possess surface properties which enable the treated sheet structure to be removed from it without becoming damaged. The porous member should be self-supporting and sufficiently porous to permit the rapid percolation of treatment fluid therethrough. Both surfaces should be made of materials inert to the treatment fluid. The rigid member and the porous member should adequately support the sheet structure during exposure to the treatment fluid and should restrain the structure from dimensional changes but excessive pressure on the structure should be avoided.

The treatment fluid is of course selected to fulfill the desired treatment of the sheet structure and may be applied at am- A preferred embodiment of the invention, incorporating means to vary the pressure exerted on the sheet structure during treatment is shown in FlGSYl and 2 of the accompanying drawing, wherein FIG. I shows a section through the apparatus parallel to the direction of forwarding of the sheet structure and FIG. 2 shows a detail of the treatment zone.

In the Figures, reference numeral 2 represents a cylindrical roll having a nondeformable, impermeable surface and reference numerals 3, 4, 5 represent cylindrical rolls around which passes a porous endless belt 6. Rolls 2, 3, 4 are mounted in supporting end-frames (not shown) in such positions that endless belt 6 lies in contact for a selected distance with the surface of roll 2. Roll 5 is supported by endless belt 6 and is provided with an axle (not shown) the ends of which are located in vertical slots vertically below the axis of roll 2 in the end-frames (not shown) so that the roll 5 is movable in a vertical direction. Provision is also made for loading roll 5 with weights 7 which are supported by tray 8 dependent from the axis of roll 5, or alternatively by pneumatic or hydraulic means (not shown). By this means the tension in belt 6 and hence the pressure between belt 6 and the surface of roll 2 can be varied as desired. A trough 9 is rigidly mounted below belt 3 and roll 2. The trough 9 is provided with end walls (not shown) which are made of an inert low-friction material and are machined at their outer ends to conform closely to the contours of belt 6 as it is in contact with roll 2. Flexible seals ll, 12 are attached to transverse walls l3, 14 of trough 9 and bear firmly against the underside of belt 6. Vapor is supplied to the trough 9 by means of supply pipe 10, and vapor condensate may be removed by way of drain pipe 18. Alternatively trough 9 may be partially filled with a fluid in liquid form (which may be recirculated if desired) and the vapors above the liquid then constitute the treatment fluid.

In operation the trough 9 is filled with treatment fluid and the sheet structure to be treated is introduced between belt 6 and roll 2. One of rolls 2, 3 and 4 is positively driven at a speed determined by the length of the treatment zone, the duration of the treatment required and the rate of supply of the sheet structure. After treatment the structure is withdrawn from between roll 2 and belt 6.

The roll 9 is provided with a smooth, nondeformable, nonporous surface and is conveniently manufactured from metals or alloys. Stainless steel is preferred. The endless belt 6 should conform readily to the profile of roll 9. Woven materials such as canvas or woven wire, such as phosphor-bronze wire, are suitable.

The apparatus is suitable for the treatment of delicate sheet structures such as textile materials, in particular nonwoven textile materials. in our South African Pat. No. 2802/69 we describe and claim, interalia, the manufacture of a nonwoven fabric comprised of continuous filaments of a synthetic organic polymer, the filaments possessing the ability to increase in length when treated with heat, solvent or swelling agents, while the web is restrained, under low mechanical pressure,

from overall change in dimensions while the filaments increase in length.

In a preferred embodiment the continuous filaments are freshly spun polyamide filaments which are capable of increasing their length of exposure to heat or moisture and do so rapidly on exposure to steam. The apparatus of the present invention is eminently suitable for the treatment of the webs described in South African Pat. No. 2802/69. (Case 8.73 l

The invention is further described in the following example, which exemplifies the use of the apparatus in the treatment of a nonwoven web comprising continuous freshly spun polyamide filaments with an atmosphere of saturated steam at low mechanical pressures.

EXAMPLE A web weighing 127 g. cm. was made from continuous, bicomponent filaments, in which the components of the filaments were arranged in a concentric core and sheath configuration. The core consisted of nylon 6.6 and the sheath was a copolymer of 70 percent hexamethylene adipamide and 30 percent e-caprolactam: the ratio of the weights of core: sheath was 65:35. A first portion A of the web was passed, within 5 minutes of spinning of the constituent filaments, through a steam treatment apparatus as illustrated in the figures accompanying this specification. The roll 2 was manufactured of stainless steel, with provision for internal heating by steam and had a diameter of 31 cm. The belt 6 was a 65/195 triple weave phosphor-bronze woven wire belt supplied by Messrs. C. H. Johnson and Sons Ltd, Wythenshawe, Manchester, England and the belt ran in contact with the roll 2 so as to subtend an angle of 120. By adjusting the weight applied to belt 2 by roll 5 a pressure of 5.25 g. cm. was exerted upon the web. The temperature of the roll 2 was maintained at 60 C., the rate of travel of the web through the apparatus was 62 cm. min. and the wrapped portion of the roll, with the web, was exposed to a moist, hot aqueous atmosphere obtained by circulating water at 95 C. through trough 9.

A second portion B of the same web was passed through the apparatus under an applied pressure of 14.6 g. emf, all other conditions being unaltered.

The properties of samples A and B were compared with a sample C of untreated material.

Samples A and B were found to have a crepe pattern on their surfaces whereas no such pattern could be detected on sample C. Additionally samples A and B had a higher resistance to damage when handled than sample C as is shown by the load extension characteristics recorded in the following table. The characteristics were obtained from analysis of the trace produced by an lnstron tensile tester. The test sample was 10 cm. long by 2.5 cm. wide and the rate of extension was 10 cm./min.

lclaim: 1. Apparatus for the continuous treatment with gaseous fluid of delicate nonwoven fabric sheet structures comprised of continuous filaments capable of self-elongation in steam, said apparatus comprising: a nondeformable impervious movable member and a porous, conformable, movable member, both members being arranged to move at the same surface speed as the sheet structure and to grip the sheet structure therebetween, wall means defining with that part of the porous member which it is in contact, a chamber within which the treatment fluid is maintained whereby fluid in the chamber passes through said porous movable member, and means for effecting a pressure of 3.5 to I40 grams per square centimeter between said movable members.

2. Apparatus for the continuous treatment with gaseous fluid of delicate nonwoven fabric sheet structures comprised of continuous filaments capable of self-elongation in steam, said apparatus comprising a rotatably mounted roll provided with a nondeformable, impervious surface, an endless belt of a porous nature, said belt being arranged to contact the surface of the said roll over a part of its circumference, mear s for adjusting the tension in said belt so that the pressure exerted by the belt upon the roll may be selected at will in the range 3.5 to I40 grams per square centimeter, and a trough situated beneath the belt and in close contact therewith over at least part of the distance where belt and roll are in contact and means for supplying fluid to the trough either in gaseous or in liquid form so that gaseous fluid may percolate through the belt.

3. Apparatus as claimed in claim 2 wherein the roll is internally heated.

4. Apparatus as claimed in claim 2 wherein the roll [8 

1. Apparatus for the continuous treatment with gaseous fluid of delicate nonwoven fabric sheet structures comprised of continuous filaments capable of self-elongation in steam, said apparatus comprising: a nondeformable impervious movable member and a porous, conformable, movable member, both members being arranged to move at the same surface speed as the sheet structure and to grip the sheet structure therebetween, wall means defining with that part of the porous member which it is in contact, a chamber within which the treatment fluid is maintained whereby fluid in the chamber passes through said porous movable member, and means for effecting a pressure of 3.5 to 140 grams per square centimeter between said movable members.
 2. Apparatus for the continuous treatment with gaseous fluid of delicate nonwoven fabric sheet structures comprised of continuous filaments capable of self-elongation in steam, said apparatus comprising a rotatably mounted roll provided with a nondeformable, impervious surface, an endless belt of a porous nature, said belt being arranged to contact the surface of the said roll over a part of its circumference, means for adjusting the tension in said belt so that the pressure exerted by the belt upon the roll may be selected at will in the range 3.5 to 140 grams per square centimeter, and a trough situated beneath the belt and in close contact therewith over at least part of the distance where belt and roll are in contact and means for supplying fluid to the trough either in gaseous or in liquid form so that gaseous fluid may percolate through the belt.
 3. Apparatus as claimed in claim 2 wherein the roll is internally heated.
 4. Apparatus as claimed in claim 2 wherein the roll is fabricated from stainless steel.
 5. Apparatus as claimed in claim 2 wherein the belt is fabricated of a woven fabric.
 6. Apparatus as claimed in claim 5 wherein the belt is a canvas.
 7. Apparatus as claimed in claim 5 wherein the belt is a woven metallic wire fabric.
 8. Apparatus as claimed in claim 5 wherein the metallic wire is a phosphor-bronze alloy.
 9. Apparatus as claimed in claim 2 wherein the trough is provided with seals which bear upon the belt.
 10. Apparatus as claimed in claim 2 wherein the base fluid is saturated steam. 